To the Editor: Adults with attention defi cit hyperactivity disorder (ADHD) experience sustained attention defi cits manifested with accompanying diffi culties completing tasks. 1,2 While ADHD symptoms cause signifi cant impairment, many affected adults remain untreated. 1 Efforts to improve recognition and management include the development of ADHD symptom scales for screening and treatment monitoring of these patients. 1 In the recent commentary by Drs. Manos and Short, 2 task incompletion is regarded as the primary dysfunction in adults. Accordingly, the authors suggest that task completion should be used as a measure to track pharmacologic therapy response in these patients. This is conceptually plausible since several adult ADHD diagnostic criteria relate to task completion, eg, "reluctance to start or to persist with tasks requiring sustained mental effort." 3 Clinical assessments to help evaluate task completion diffi culties include the use of continuous performance tests (CPTs), which can measure attention and require the individual to respond to targets (a measure of attention) and to inhibit response to non-targets (a measure of impulsivity). 4 Marchetta et al 5 found a deterioration of timeon-task in adults with ADHD relative to controls. Babajanyan et al 3 noted 3 patterns that decreased task completion. These patterns included complete lapses in attention, partial attention to a task, and engaging in multiple tasks. However, disagreement exists on whether the ability to stay on task as measured by CPTs can accurately refl ect the severity of ADHD. Baggio et al 6 examined CPTs as a marker of adult ADHD presentation and severity and reported small correlations